1. Field of the Invention
The present invention relates to a wire-wound chip inductor, and more particularly, to a wire-wound chip inductor in which a magnetic plate for increasing inductance is attached to a member for holding a wire.
2. Description of the Related Art
FIGS. 7 and 8 show a first example of a conventional wire-wound chip inductor.
A wire-wound chip inductor 1 shown in FIGS. 7 and 8 comprises a wire holding member 6 having a core portion 3 with a wire 2 wound therearound, and flange portions 4 and 5 projecting from both ends of the core portion 3 in the axial direction, and a magnetic plate 7 attached to the wire holding member 6 to connect the flange portions 4 and 5 thereto.
The above elements of the wire-wound chip inductor 1 have respective widths extending in the same direction, which direction intersects the axial direction of the core portion 3. Specifically, the outer periphery of the wire 2 has a width W1, the core portion 3 has a width W2, the flange portions 4 and 5 have a width W3, and the magnetic plate 7 has a width W4, as shown in FIGS. 7 and 8.
The width W2 of the core portion 3, the width W3 of the flange portions 4 and 5, and the width W4 of the magnetic plate 7 are equal to each other. Therefore, the width W1 of the outer form of the wire 2 is larger than these widths W2, W3, and W4.
FIGS. 9 and 10 show a second example of a conventional wire-wound chip inductor.
Similarly to the conventional wire-wound chip inductor 1 described above, a wire-wound chip inductor 11 shown in FIGS. 9 and 10 comprises a wire 12, a core portion 13, flange portions 14 and 15, a wire holding member 16, and a magnetic plate 17. The outer periphery of the wire 12 has a width W1, the core portion 13 has a width W2, the flange portions 14 and 15 have a width W3, and the magnetic plate 17 has a width W4.
While the width W3 of the flange portions 14 and 15 and the width W4 of the magnetic plate 17 are equal to each other in the wire-wound chip inductor 11, the width W2 of the core portion 13 is smaller than the width W3 of the flange portions 14 and 15, which is different from the wire-wound chip inductor 1 described above. Therefore, the width W1 of the outer periphery of the wire 12 can be made smaller than the width W3 of the flange portions 14 and 15 and the width W4 of the magnetic plate 17.
In the wire-wound chip inductor 1 shown in FIGS. 7 and 8, as mentioned above, the width W2 of the core portion 3, the width W3 of the flange portions 4 and 5, and the width W4 of the magnetic plate 7 are equal. Therefore, the widths W2 to W4 define the outer periphery of the entire wire-wound chip inductor 1. In other words, the width W2 of the core portion 3 is equal to the outermost width of the wire-wound chip inductor 1. When the width W2 of the core portion 3 is large enough to be equal to the outermost width of the wire-wound chip inductor 1, however, the length of one turn of the wire 2 increases, and a relatively large amount of stray capacitance thereby arises between adjacent portions of the wire 2. This deteriorates the characteristics at high frequencies.
Moreover, since the width W1 of the outer periphery of the wire 2 is larger than the width W3 of the flange portions 4 and 5 or the width W4 of the magnetic plate 7, when the wire-wound chip inductor 1 is handled via a chuck or the like in mounting or in other situations, the wire 2 is prone to be scratched. For this reason, an insulating coating on the wire 2 may be undesirably stripped or the wire 2 may be broken.
On the other hand, according to the wire-wound chip inductor 11 shown in FIGS. 9 and 10, since the width W2 of the core portion 13 is smaller than the width W3 of the flange portions 14 and 15, namely, the outermost width of the wire-wound chip inductor 11, as mentioned above, the stray capacitance between adjacent portions of wire can be reduced. In addition, since the width W1 of the outer periphery of the wire 12 can be made smaller than the width W3 of the flange portions 14 and 15 or the width W4 of the magnetic plate 17, it is possible to solve the problem of the wire 12 being scratched during handling of the wire-wound chip inductor 11.
In the wire-wound chip inductor 11, however, since the width W2 of the core portion 13 is smaller than the width W3 of the flange portions 14 and 15, the process of forming the wire holding member 16 including the core portion 13 and the flange portions 14 and 15 is complicated, which increases the manufacturing cost.